Sewing thread and method of treating



2,888,365 Egfi Patented May 1959' SEWING THREAD AND METHOD OF TREATING Howard D. Corkum, Willimantic, Conn., assignor to The American Thread Company, New York, N.Y., a corporation of New Jersey No Drawing. Application April 17, 1957 Serial No. 653,301

11 Claims. (Cl. 117- 76) The present invention relates to sewing thread, and has special reference to sewing thread and bobbins for use in sewing machines, and further relates to a method of manufacturing such thread and bobbins.

in the manufacture of bobbins for sewing machines, the thread is commonly cross or universal wound, and

after winding the bobbins are compressed from twenty to thirty percent so as to permit the maximum amount of thread to be used for the size of the bobbin case. The bobbins may have a central core with disks secured on the ends of the core against the mass of wound thread, or the bobbins may be without disks. Also, the bobbins may be coreless and unwound from their centers.

Heretofore, difiiculty has been experienced due to the tendency of the thread in the bobbin to overrun or spill from the thread mass during use of the bobbins in sewing machines, and in the case of bobbins provided with end disks to work down between the disks and the thread mass.

One of the objects of the present invention is to provide a sewing thread having a coating of such a nature that when the thread is wound and the bobbin compressed, the thread is effectively held to the thread mass by the correct amount of tack so that it is IE1. part of the mass up to the moment it is drawn away.

Another of the objects of the invention is to provide a novel and improved bobbin for sewing machines.

Still another of the objects of the invention is to provide a novel and improved method of treating sewing thread, and manufacturing bobbins for sewing machines.

In accordance with the present invention, the thread is first coated with a pressure-sensitive adhesive. An adhesive of this character which I have found satisfactory is one put out by Angier Products, Inc., under the designation of No. P.S.M. 271-1. This specific material falls in the category of a polyvinyl ether derivative. The material when applied to thread as hereinafter described, crosswound into a bobbin, and the bobbin compressed, provides a surface condition having practically perpetual tackiness or adhesiveness of the desired degree at normal temperatures and to substantially 300 F. This material is prepared in a solvent which may be removed by heat after the thread is coated and before the bobbin is wound.

Various other pressure sensitive adhesives, however, may be used having the characteristics mentioned. Such adhesives may be prepared from rubber or resin or resinlike materials, or a mixture thereof with pigment materials, such as carbon black and zinc oxide. The composition may involve a natural or synthetic rubber with a resinous material, such as hydrogenated rosins, esters and resinlike materials, either in composition with elastomeric or resin reinforces. These adhesive compositions may be diluted with a solvent vehicle which would normally fall into the classification of aromatic or aliphatic solvents, which are desirable or necessary to facilitate the coating of the perpetually tacky compound to the surface of the sewing thread.

The pressure-sensitive adhesive coating may be applied by drawing the thread through it, squeezing off the excess, and running the thread through a heated chamber to remove all of the solvents.

Preferably the amount of the pressure-sensitive adhesive employed is 2 /2 of the weight of the thread. However, the thickness of this coating may be varied substantially from 1 to 5% of the thread weight.

After the pressure-sensitive adhesive has been run through the heated chamber as described, and is thus dried,

I apply a second coating over the first coating. This second coating preferably comprises microcrystalline wax. This wax is more ductile and tacky than paraffin wax, but less tacky than the pressuresensitive adhesive described, and has a slight degree of lubricating properties. I have found that microcrystalline wax put out by the City Service Company under the designation Micro Wax 30 produces satisfactory results. This wax may be applied in any suitable manner as by running it through a hot melt or over a solid disk.

This second Micro Wax coating is preferably substantially thinner than the first coating. I have found that substantially 1% by weight of the wax coating is satis factory where the first coating is 2 /2%.

The thread thus coated and cross-wound into a bobbin, and the bobbin compressed at normal temperature, results in the thread being held to the thread mass by the correct degree of tack so that it is a part of the mass up to the moment it is drawn away. The tackiness of the surface of the thread of this compressed bobbin insures that when the bobbin is used in a sewing machine, the unwound portion thereof holds its shape and the thread is withdrawn in a free even flow, forming an even stitch due to the uniform control and release of the thread from the bobbin, and the lubricating properties of the outer coating. These combined characteristics are necessary for smooth operation and elimination of the undesirableproperties of normal thread of overrunning or spillage from the thread mass, causing ravelling, pulling down between the disks when disk bobbins are employed, as well as those faults of resinous treated threads which, because of the nature of such a treatment, holds firmly to the thread mass at normal temperatures requiring a greater load that develops into greater and uneven tensions when the thread is pulled from the thread mass of the bobbin.

My improved coated thread allows a bobbin to be made which will fill the bobbin case to its fullest capacity, and thus permits the maximum amount of thread to be employed.

The coatings as described may be used with cotton threads, or synthetic threads, and have the same operating advantages.

The coatings reduce any liveliness of the thread that may be present, and reduce the tendency of the thread mass to change in size after the bobbin is made and compressed, thus stabilizing the bobbin for size under varying conditions of temperature and moisture.

i have found that bobbins thus made with the thread coated as described, will effectively withstand the heat that might be developed in using the bobbins in high speed sewing machines or in heavy work, and also is not affected by oil coming into contact with the thread. It has been found that if microcrystalline wax alone is used in the coating, some sewing machines develop so much heat that the wax is melted and then the adhesiveness of the wax is lost, and the bobbin breaks down and the effectiveness of the \adhesiveness of the wax coating is destroyed. Also, when the thread is coated with microcrystalline wax alone the bobbin is likely to break down when too much oil is applied to the bobbin.

These difficulties are eifectively overcome by first coating the thread with the pressure-sensitive material as described, and then applying the protective wax coating. Bobbins thus made, even without disks, do not break down because of handling, heat developed by the sewing machine, or oil from the sewing machine coming into contact therewith. With the two coatings as described, even though the heat developed melts the thin micro-wax coating, or oil may release the holding power of the wax, the pressure-sensitive undercoating is not affected and the bobbin will stand up. The rnicrowax coating tends to mask the tack of the pressure-sensitive adhesive so that the adhesive does not interfere with the winding of the thread, or the use of the thread in sewing. The wax makes it possible to wind bobbins in the standard manner, then when the bobbins are pressed the pressure-sensitive adhesive takes over as described.

What I claim is:

1. A sewing thread of the kind described having a coat ing of pressure-sensitive adhesive, and a second coating of microcrystalline wax over the first coating.

2. A sewing thread in accordance with claim 1 in which the first coating is substantially two and one-half percent by weight of the thread, and the second coating is substantially one percent of the weight of the thread.

3. A sewing thread in accordance with claim 1 in which the first coating remains tacky at normal temperatures and at elevated temperatures of upwards of 200 F.

4. The method of treating sewing thread for bobbins of sewing machines which comprises coating the thread with a pressure-sensitive adhesive, drying the thus coated thread, and applying a coating of microcrystalline wax over the first coating.

5. An article comprising a sewing thread having coated thereon a pressure-sensitive adhesive of a derivative of polyvinyl ether, and a coating of microcrystalline wax superimposed on the said adhesive.

6. An article comprising a sewing thread having coated thereon a pressure-sensitive adhesive of a derivative of polyvinyl ether, said adhesive coating being about one to five percent by weight of the thread, and a coating of microcrystalline wax superimposed on the said adhesive.

7. An article comprising a sewing thread having coated thereon a pressure-sensitive adhesive of a derivative of polyvinyl ether, said adhesive coating being about one to five percent by weight of the thread, and a coating of microcrystalline wax superimposed on the said adhesive, said wax coating being substantially thinner than said adhesive coating.

8. An article comprising a sewing thread having coated thereon a pressure-sensitive adhesive of a derivative of polyvinyl ether, said adhesive coating being about two and one-half percent by weight of the thread, and a coating of microcrystalline wax superimposed on the said adhesive, said wax coating being about one percent by weight of the thread.

9. The method of treating sewing thread for bobbins of sewing machines which comprises coating the thread with a pressure-sensitive adhesive of a derivative of polyvinyl ether, drying the thus coated thread, and applying a coating of microcrystalline wax over the adhesive coating.

10. The method of treating sewing thread for bobbins of sewing machines which comprises coating the thread with a pressure-sensitive adhesive of a derivative of polyvinyl ether until the coating is about one to five percent by weight of the thread, drying the thus coated thread, and applying a coating of microcrystalline wax over the adhesive coating which is substantially thinner than the adhesive coating.

11. The method of treating sewing thread for bobbins of sewing machines which comprises coating the thread with a pressure-sensitive adhesive of a derivative of polyvinyl ether until the coating is about two and one-half percent by weight of the thread, drying the thus coated thread, and applying a coating of microcrystalline wax over the adhesive coating until the wax coating is about one percent by weight of the thread.

References Cited in the file of this patent UNITED STATES PATENTS 2,200,721 Marinsky May 14, 1940 2,203,286 Simpson June 4, 1940 2,674,215 Thompson et al Apr. 6, 1954 2,732,817 Robinson Jan. 31,, 1956 

1. A SEWING THREAD OF THE KIND DESCRIBE HAVING A COATING OF PRESSURE-SENSITIVE ADHESIVE, AND A SECOND COATING OF MICROCRYSTALLINE WAX OVER THE FIRST COATING. 